Mouse becomes "trapped" in a box unless I use the xrandr scaling option
 

On my Cherry Trail PC stick I have noticed that the mouse cursor can not move across the entire screen. But if I use the scaling option in xrandr, for example, --scale 1x1.001 , the mouse becomes free. But this makes text look less clear. What could be the problem here?

What OS is on this system?

Have you looked in the log files, particularly the /var/log/Xorg.?.log?

Devuan 2 "Ascii" is the OS but I am running a 4.9.x kernel for working sound on Cherry Trail devices.

This has been a really bad bug to troubleshoot. To clear up the boundary description, it seems to just make the cursor disappear not the logical pointer of the mouse itself. It is enough to make things feel confusing and buggy though. Additionally, this bug is present on "Right" and "Inverted" orientation at any resolution and not present on "Left" and "Normal" orientation.

Ultimately I found out that the "panning" option in xrandr should free the mouse up as well. It does work sometimes but only if the mouse has been parked in an expanded area beyond the previous or perhaps native resolution. To automate this and have the touchscreen (and mouse pointer) have full travel upon login I edited my startup script as follows. First I set my resolution and orientation and set an expanded viewing area with the panning option. Then I had xdotool move the mouse cursor into the expanded area. Then finally I set resolution and orientation again and set the panning option to 0x0.

This did not seem perfectly reliable across reboots but I think I have it now. It worked three times in a row after shutdown. I could not guarantee it will keep working though. I cannot tell you what the issue is directly but it should not be working like this.